Large‐Scale Surfactant Exfoliation of Graphene and Conductivity‐Optimized Graphite Enabling Wireless Connectivity

Abstract

Graphene and other graphitic materials are suggested as a route to cheap, high‐performance, environmentally‐sustainable electronic devices owing to their almost unique combination of properties. Liquid‐phase exfoliation is a family of shear‐based techniques that produce dispersions of nanosheets from bulk layered material crystallites. High‐quality nanosheets of graphene can be produced in solvents or surfactant dispersions; however the lateral size of these sheets limits the network transport properties observed in printed films. A high‐throughput, industrially‐scalable aqueous process for the production of graphene and related layered nanomaterials is presented. By considering not only the exfoliation process, but also the size selection and deposition processes, printable graphitic nanoparticulate materials with conductivities up to 50 000 S m−1 are demonstrated. This value is ten times larger than is typically obtained for few‐layer graphene produced by liquid‐phase exfoliation. The size selection process is critical to obtaining the maximum conductivity of deposited films, with an optimized nanographite having greater performance than few‐layer graphene or graphite that is processed and used without size selection. Building on these results a radio‐frequency antenna application is demonstrated, which is competitive with the state‐of‐the‐art, and a route to recycling of such printed short‐lifetime electronic devices to lower the environmental impact is discussed.

Graphene-based printable conductors for cyclable strain sensors on elastomeric substrates

“…Graphene was produced by high shear exfoliation in a Mini DeBEE homogenizer from BEE International at 35kpsi for 10 passes using 60g/L graphite to 4g/L Triton X-100 (CAS# 9002-93-1). Full details of the dispersion procedure are published in previous work [22]. The material was centrifuged at 5000g for 6 minutes to remove large aggregates and then centrifuged at 5000g for 1 hour to remove the few layer graphene as well as leave unbound surfactant in the supernatant.…”

Langmuir Films of Layered Nanomaterials: Edge Interactions and Cell Culture Applications

“…Graphene dispersions in cyclohexanone were processed as described in Large et al 24 . Sizeselected graphene dispersions were required.…”

Microfluidics for Two-Dimensional Nanosheets: A Mini Review

“…It is a general perception that the electrical conductivity of films constituted with exfoliated graphene nanosheets is low owing to the smaller lateral size and presence of surfactants. Large et al recently reported a printed graphene film with excellent conductivity up to 50,000 S/m, which is one order of magnitude higher than that reported by Karagiannidis et al [49]. The printable graphene ink was prepared via a high-pressure homogenization process (microfluidization), enabling a high throughput of 0.5 g h −1 graphene nanosheet production, equivalent to almost 5 kg of graphene nanosheets per year.…”